I have sometimes wondered if technology could be used to make some house-elves more visible. When I buy an apple or some meat in the grocery store they are simply opaque to me. Their production is completely invisible. Was it a farmer in my home country who produced it, driving around in his comfortable tractor, or was it a hard pressed third world farmer whose children go uneducated despite his best efforts? Knowing this through some technological means, even to an imperfect degree, would probably affect my choices.